JPH03198079A - Electrophotographic device - Google Patents

Abstract

PURPOSE:To always obtain stable image quality without the occurrence of defective transfer with the stain of charging wire, etc., by developing a reference density pattern onto an electrostatic latent image carriers detecting the density of a batch image transferred on a transfer belt and that of a batch image transferred on the electrostatic latent image carrier with a first and a second detecting means respectively, comparing them with a reference value, and adjusting an output from a belt electrifying means. CONSTITUTION:After the reference density pattern 18 is exposed on the electrostatic latent image carrier 2 by an exposure means 15, and is developed by a developing means 3, this image is transferred onto the transfer belt 5. The density of the transferred batch image is detected by a first sensor 19 while the density of the batch image which was not transferred onto the transfer belt 5 remains on the electrostatic latent image carrier 2 is detected by a second sensor 20. A control means 21, for which the detected densities are inputted, compares its ratio with the previously set reference value, and adjusts the output from the belt electrifying means 6 based on the result. Thus, stable image quality is always obtained without the occurrence of defective transfer, which is caused with the stain of the charge wire, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention This invention relates to an electrophotographic apparatus equipped with a transfer conveyor belt.

BACKGROUND OF THE INVENTION Conventional electrophotographic devices such as transfer chargers and separation chargers that perform transfer and separation using a corotron system have difficulty adapting uniformly to changes in environmental conditions and to a wide variety of transfer papers, resulting in problems with toner image quality. There have been problems in that paper jams and the like occur due to turbulence and poor separation.

Therefore, an electrophotographic device equipped with a transfer conveyance belt was proposed as an electrophotographic device capable of solving these problems.
Since it has many parts in common with the embodiment of the invention shown in the drawings, its outline will be explained with reference to it.

It consists of an electrostatic latent image carrier 2, a charging means 1 for imparting an electric charge to the electrostatic latent image bearer 2, and the charged electrostatic latent image bearer 2 set on a document table 13. Manuscript 1
2, a developing means 3 for supplying charged toner to the electrostatic latent image, and a transfer material supply means for supplying the transfer material 14 to the electrostatic latent image carrier 2. and a transfer means 4 for transferring the toner image onto a transfer material 14.
The transfer means 4 includes an endless transfer conveyance belt 5, a belt charging means 6 for applying an electric charge of opposite polarity to the charged polarity of the toner to the transfer conveyance belt 5, and the transfer conveyance belt 5. and drive means for driving.

(See JP-A-63-85666 as an example). Note 7
8 represents a cleaning means, 8 represents an eraser, and IO represents a light source.

In the electrophotographic apparatus described above, the original 12 placed on the original platen 13 is scanned by a light source 1O in the direction shown by arrow a in FIG. The exposure means 15 is charged with a high voltage in advance by the charging means 1, and guided to the electrostatic latent image carrier 2 which rotates in the direction of the arrow 2 in synchronization with the scanning to form a latent image thereon.

The developing means 3 then develops the latent image with toner, and the transfer means 4 transfers the toner image on the electrostatic latent image carrier 2 onto the transfer material 14 fed from the direction of arrow C.

Such a transfer means 4 has an electrical resistance of 1010 to 10!
The transfer conveyor belt 5 is provided with an endless transfer conveyor belt 5 having a portion made of a semiconductor material of 3 Ωcm, and a belt charging means 6 for applying an electric charge of opposite polarity to the charge polarity of the toner to the transfer conveyor belt 5. The belt 5 is urged toward the electrostatic latent image carrier 2 by a biasing member (not shown), and the charging means 6 is disposed near a portion where the electrostatic latent image carrier 2 and the transfer conveyance belt are close to each other. There is.

When transferring onto the transfer material 14, the belt charging means 6 applies an electric charge to the semiconductor material portion of the transfer conveyance belt 5, thereby preventing the transfer material 14 from becoming static without directly applying an electric charge to the transfer material 14. The transfer material 14 is attracted onto the transfer conveyance belt 5 and conveyed by the electrostatic attraction between the polarized charge caused by electrical induction and the true charge of the transfer conveyance belt 5 . The toner transfer at this time is performed by making the charge that the belt charging means 6 applies to the transfer conveyance belt 5 have a polarity opposite to the charge that the toner on the electrostatic latent image carrier 2 has.

Problems to be Solved by the Invention Incidentally, in such an electrophotographic apparatus, since the transfer conveyance belt 5 also uses a belt charging means 6 based on a corotron system when transferring toner, changes in environmental conditions, Alternatively, the output of the belt charging means 6 may change due to contamination of the charge wire, which is the belt charging means 6, resulting in transfer failure, making it difficult to maintain stable image quality at all times.

Therefore, an object of the present invention is to solve the problems of the conventional electrophotographic apparatus, and to maintain stable image quality and conveyance conditions at all times without causing transfer defects due to changes in environmental conditions or dirt on the charge wire. The object of the present invention is to provide an electrophotographic device that is highly reliable and has a simple configuration.

Means for Solving the Problems In order to achieve the above-mentioned object, the present invention provides an electrophotographic apparatus equipped with the previously proposed transfer conveyance belt, in which an electrostatic latent image carrier is exposed to light by the exposure means on the document table. a first detection means for detecting the density of the batch image transferred onto the transfer belt based on the image developed on the electrostatic latent image carrier of the reference density pattern;
a second detection means for detecting the density of the batch image remaining on the electrostatic latent image carrier after being transferred to the transfer belt; It is characterized by comprising a control means for inputting the concentration output from the second detection means, comparing the ratio with a predetermined reference value, and adjusting the output from the belt charging means. It is something to do.

Function: In the apparatus of the present invention as described above, the reference density pattern is exposed to the electrostatic latent image carrier by the exposing means and developed by the developing means, and then this image is transferred onto the transfer belt, and the transferred image is transferred to the transfer belt. The density of the batch image is detected by the first detection means, and the density of the batch image remaining on the electrostatic latent image carrier without being transferred onto the transfer belt is detected by the second detection means. The control means, which receives the concentration detected by the belt charging means, compares the ratio with a preset reference value, and adjusts the output from the belt charging means based on the result.

Embodiment In the embodiment shown in the drawings, the same parts as those of the previously proposed one are given the same reference numerals, and the explanation thereof will be omitted, and the other parts will be mainly explained.

Reference numeral 18 indicates a reference density pattern provided outside the document placement area of the document table 13, and is composed of, for example, a black pattern with a density of 1.80. 19 is a first sensor for detecting toner concentration on the transfer conveyance belt 5; 20 is a second sensor for detecting toner concentration on the electrostatic latent image carrier 2; and 21 is a sensor for detecting detection signals from these sensors 19.2G. and control means for adjusting the output of the belt charging means 6, respectively;
16 is a container for collecting the toner on the transfer conveyance belt 5, and 17 is a blade for scraping off the toner.

The operation of the above will be explained with reference also to the flowchart shown in FIG.

After the electrostatic latent image carrier 2 is exposed to light by the exposure means 15, the latent image forming area is neutralized by the eraser 8, and the latent image of the reference density pattern 18 is erased at times other than 1On+1 copy cycle from turning on the main switch. Ru. In this way, the latent image of the reference density pattern 18 is formed on the electrostatic latent image carrier 2 every 10n+1 copy cycles after the main switch is turned on, and is visualized by the developing means 3.

This developed image is transferred onto the transfer conveyor belt 5 by the belt charging means 6 in the same way as in the previously proposed one, and the first sensor 19 detects the transferred batch image of the reference density pattern to determine the density. Output VSt. Separately, the batch image remaining on the electrostatic latent image carrier 2 without being transferred onto the transfer conveyance belt 5 is detected by the second sensor 20, and its density VSP is output. In this case, under normal and suitable conditions, vST, vS are each 0.5V,
4V, resulting in VST/VSF=0.5/4=
0.125, the total current of the belt charging means 6 at that time is -350 μA.

If the output of the belt charging means 6 decreases for some reason and a transfer failure occurs, the batch image density on the electrostatic latent image carrier 2 becomes darker, VST increases, and
SP becomes smaller.

Therefore, these VST and VSF are input to the control means 21, and the ratio thereof is set to the upper and lower reference values A,
If the ratio is between them, it is left as is, and if it exceeds the upper reference value A, the control means 21
Accordingly, the output of the belt charging means 6 is increased, and conversely, when the value falls below the lower reference value B, the output of the belt charging means 6 is decreased.

To give an actual example in this case, (1)
Belt charging means 6 when Vst/Vsp>AmO, 2
Since the total current is -375 μA, if such a state continues, 25 μA is added to the output of the belt charging means 6 by a command from the control means 21 so that the current becomes -350 μA under the above-mentioned appropriate conditions. Even if this additional amount increases, it should not exceed -500 μA.

(2) When VST/VSP< B = 0.1, the total current of the belt charging means 6 is -325 μA, so 2
Make it so that it decreases by 5μA.

In this way, the control means 21 receives the upper and lower reference values A.

B is set to 0.2 and 0.1, respectively, and Vst
/VSP is set to B=0.1≦V s7/V Sr≦0.2=A.

When toner is continuously supplied from the developing means 3 to the electrostatic latent image carrier 2 in this manner, the amount of toner in the developing means 3 naturally decreases, and as a result, the image becomes thinner. In this case, since the total amount of VST and Vsp will be lower than the predetermined value, toner will be replenished into the developing means 3 in the same manner as in the conventional method.

Effects of the Invention The present invention is as described above, in which a reference density pattern is developed on an electrostatic latent image bearing member, and thereby the density of the batch image transferred to the transfer belt and the electrostatic latent image bearing member is adjusted to the first. The second detection means detects this, and the control means inputs this ratio and compares the ratio with a preset reference value to adjust the output of the belt charging means. It has the advantage that it does not cause transfer defects due to dirt or the like, maintains stable image quality and conveyance at all times, has high reliability, and has a simple configuration even at 4 degrees.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional front view of a part of an embodiment of the present invention, FIG. 2 is a longitudinal sectional front view of the same part, and FIG. 3 is a flowchart of the same. 1...Charging means 3...Developing means 5...Transfer conveyance belt 12...Original 14...Transfer material 18...Reference density pattern 20...Second sensor 2...Static Latent image carrier 4...Transfer means 6...Belt charging means 13...Original platen 15...Exposure means 19...First sensor 21...Control means 6 City 1 Kaiuma 2 Figure 2 Figure 3

Claims (1)

[Claims] 1. An electrostatic latent image carrier, a charging means for imparting an electric charge to the electrostatic latent image bearer, and an image of an original set on the document table on the charged electrostatic latent image bearer. an exposure means for exposing the electrostatic latent image to light; a developing means for supplying charged toner to the electrostatic latent image; a transfer material supply means for supplying a transfer material to the electrostatic latent image carrier; a transfer means for transferring the toner to the toner; the transfer means includes an endless transfer conveyance belt; a belt charging means for applying an electric charge of a polarity opposite to the charge polarity of the toner to the transfer conveyance belt;
In an electrophotographic apparatus comprising a driving means for driving the transfer conveyance belt, a reference density pattern is provided on the original platen to be exposed onto the electrostatic latent image carrier by the exposure means, and a reference density pattern of the reference density pattern is provided. a first detection means for detecting the density of the batch image transferred onto the transfer belt by a developed image on the electrostatic latent image carrier; and a first detection means that remains on the electrostatic latent image carrier after being transferred to the transfer belt. A second detection means detects the density of the batch image, and the density output from the first and second detection means is input, and the ratio is compared with a predetermined reference value, and the belt charging means is controlled. An electrophotographic apparatus comprising: a control means for adjusting output.